usb: device_next: Add USB MTP class support

dts/bindings/fs/zephyr,fstab-common.yaml

@@ -43,3 +43,8 @@ properties:
 
       This causes the FS_MOUNT_FLAG_USE_DISK_ACCESS option to be set in
       the mount descriptor generated for the file system.
+
+  mtp-enabled:
+    type: boolean
+    description: |
+      Provide File system access over USB MTP Protocol

include/zephyr/usb/usb_ch9.h

@@ -264,6 +264,7 @@ struct usb_association_descriptor {
 #define USB_BCC_AUDIO			0x01
 #define USB_BCC_CDC_CONTROL		0x02
 #define USB_BCC_HID			0x03
+#define USB_BCC_IMAGE                   0x06
 #define USB_BCC_MASS_STORAGE		0x08
 #define USB_BCC_CDC_DATA		0x0A
 #define USB_BCC_VIDEO			0x0E

samples/subsys/usb/mtp/CMakeLists.txt

@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(mtp)
+
+include(${ZEPHYR_BASE}/samples/subsys/usb/common/common.cmake)
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})

samples/subsys/usb/mtp/Kconfig

@@ -0,0 +1,9 @@
+# Copyright (c) 2023 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+# Source common USB sample options used to initialize new experimental USB
+# device stack. The scope of these options is limited to USB samples in project
+# tree, you cannot use them in your own application.
+source "samples/subsys/usb/common/Kconfig.sample_usbd"
+
+source "Kconfig.zephyr"

samples/subsys/usb/mtp/README.rst

@@ -0,0 +1,81 @@
+.. zephyr:code-sample:: usb-mtp
+   :name: USB MTP
+   :relevant-api: usbd_api _usb_device_core_api file_system_api
+
+   Expose the selected storage partition(s) as USB Media device using Media Transfer Protocol driver.
+
+Overview
+********
+
+This sample app demonstrates the use of USB Media Transfer Protocol (MTP)
+driver provided by the Zephyr project. It allows the device to be mounted
+as a media device on the host system, enabling file transfers between the
+host and device.
+This sample can be found under :zephyr_file:`samples/subsys/usb/mtp` in the
+Zephyr project tree.
+
+Requirements
+************
+
+- USB device driver support.
+- Storage media with Littlefs/FAT filesystem support.
+- Partitions must be mounted before connecting the board to Host.
+
+Building and Running
+********************
+
+This sample can be built for multiple boards which can support at least one storage parition,
+in this example we will build it for the stm32f769i_disco board:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/subsys/usb/mtp
+   :board: stm32f769i_disco
+   :goals: flash
+   :compact:
+
+Running
+=======
+
+Plug the board into a host device, for example, a PC running Linux.
+The board will be detected as shown by the Linux dmesg command:
+
+.. code-block:: console
+
+   usb 9-1: new full-speed USB device number 112 using uhci_hcd
+   usb 9-1: New USB device found, idVendor=8086, idProduct=f8a1
+   usb 9-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
+   usb 9-1: Product: Zephyr MTP
+   usb 9-1: Manufacturer: ZEPHYR
+   usb 9-1: SerialNumber: 0123456789AB
+
+Once connected, the device should appear as a media device on your host system.
+You can then:
+- Browse the device storage
+- Transfer files to/from the device
+- Create/delete directories
+
+The storage contents will persist across device reboots as long as the
+filesystem is properly unmounted before disconnecting or resetting the device.
+
+.. note::
+
+   Not All MTP Features are implemented, for example you can't move/copy
+   files from within the device, it must be done via Host.
+
+Troubleshooting
+===============
+
+If the device is not recognized properly:
+
+1. Ensure the storage medium is properly initialized
+2. Check that the filesystem is mounted correctly
+3. Verify USB configuration is correct for your board
+4. Enable DEBUG logs on USB MTP driver to get more information
+
+For debugging purposes, you can enable USB debug logs by setting the following
+in your project's configuration:
+
+.. code-block:: none
+
+   CONFIG_USBD_LOG_LEVEL_DBG=y
+   CONFIG_USBD_MTP_LOG_LEVEL_DBG=y

samples/subsys/usb/mtp/boards/rpi_pico.overlay

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2024 Kelly Lord
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&flash0 {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		storage_partition: partition@100000 {
+			label = "storage";
+			reg = <0x100000  DT_SIZE_M(1)>;
+		};
+	};
+};
+
+/ {
+	fstab {
+		compatible = "zephyr,fstab";
+		lfs1: lfs1 {
+			compatible = "zephyr,fstab,littlefs";
+			read-size = <32>;
+			prog-size = <32>;
+			cache-size = <256>;
+			lookahead-size = <64>;
+			block-cycles = <512>;
+			partition = <&storage_partition>;
+			mount-point = "/lfs1";
+			automount;
+			mtp-enabled;
+		};
+	};
+};

samples/subsys/usb/mtp/boards/stm32f769i_disco.overlay

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2025 Mohamed ElShahawi (extremegtx@hotmail.com)
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/delete-node/ &storage_partition;
+
+&mx25l51245g {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		storage_partition: partition@1a0000 {
+			label = "storage";
+			reg = <0x001a0000 DT_SIZE_M(40)>;
+		};
+		storage_partition2: partition@2ba0000 {
+			label = "storage2";
+			reg = <0x2ba0000 DT_SIZE_M(20)>;
+		};
+	};
+};
+
+/ {
+	fstab {
+		compatible = "zephyr,fstab";
+		lfs1: lfs1 {
+			compatible = "zephyr,fstab,littlefs";
+			read-size = <32>;
+			prog-size = <32>;
+			cache-size = <256>;
+			lookahead-size = <64>;
+			block-cycles = <512>;
+			partition = <&storage_partition>;
+			mount-point = "/lfs1";
+			automount;
+			mtp-enabled;
+		};
+		lfs2: lfs2 {
+			compatible = "zephyr,fstab,littlefs";
+			read-size = <32>;
+			prog-size = <32>;
+			cache-size = <256>;
+			lookahead-size = <64>;
+			block-cycles = <512>;
+			partition = <&storage_partition2>;
+			mount-point = "/lfs2";
+			automount;
+			mtp-enabled;
+		};
+	};
+};

samples/subsys/usb/mtp/prj.conf

@@ -0,0 +1,24 @@
+CONFIG_USB_DEVICE_STACK_NEXT=y
+CONFIG_USBD_MTP_CLASS=y
+
+CONFIG_SAMPLE_USBD_PRODUCT="USBD MTP sample"
+CONFIG_SAMPLE_USBD_PID=0x0009
+
+CONFIG_LOG=y
+CONFIG_USBD_LOG_LEVEL_WRN=y
+CONFIG_UDC_DRIVER_LOG_LEVEL_WRN=y
+CONFIG_USBD_MTP_LOG_LEVEL_ERR=y
+
+CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT=n
+
+CONFIG_FLASH=y
+CONFIG_FLASH_MAP=y
+
+CONFIG_FILE_SYSTEM=y
+CONFIG_FILE_SYSTEM_LITTLEFS=y
+
+CONFIG_USBD_THREAD_STACK_SIZE=4096
+
+CONFIG_USBD_LOG_LEVEL_DBG=y
+CONFIG_USBD_MTP_LOG_LEVEL_DBG=y
+CONFIG_LOG_BUFFER_SIZE=8192

samples/subsys/usb/mtp/sample.yaml

@@ -0,0 +1,11 @@
+sample:
+  name: USB MTP device class sample
+tests:
+  sample.usb_device_next.mtp:
+    depends_on: usbd
+    tags: usb
+    harness: console
+    harness_config:
+      type: one_line
+      regex:
+        - "USB device support enabled"

samples/subsys/usb/mtp/src/main.c

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2019 Intel Corporation
+ * Copyright (c) 2025 Mohamed ElShahawi (extremegtx@hotmail.com)
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @file
+ * @brief Sample app for USB MTP class
+ *
+ * Sample app for USB MTP class driver. By default MTP class driver will expose
+ * all storage partitions which has the flag `mtp-enabled`
+ */
+
+#include <sample_usbd.h>
+
+#include <zephyr/kernel.h>
+#include <zephyr/usb/usb_device.h>
+#include <zephyr/usb/usbd.h>
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(usb_mtp_sample, LOG_LEVEL_INF);
+
+static void sample_msg_cb(struct usbd_context *const ctx, const struct usbd_msg *msg)
+{
+	LOG_INF("USBD message: %s", usbd_msg_type_string(msg->type));
+
+	if (usbd_can_detect_vbus(ctx)) {
+		if (msg->type == USBD_MSG_VBUS_READY) {
+			if (usbd_enable(ctx)) {
+				LOG_ERR("Failed to enable device support");
+			}
+		}
+
+		if (msg->type == USBD_MSG_VBUS_REMOVED) {
+			if (usbd_disable(ctx)) {
+				LOG_ERR("Failed to disable device support");
+			}
+		}
+	}
+}
+
+int main(void)
+{
+	struct usbd_context *sample_usbd;
+
+	sample_usbd = sample_usbd_init_device(sample_msg_cb);
+	if (sample_usbd == NULL) {
+		LOG_ERR("Failed to initialize USB device");
+		return -1;
+	}
+
+	if (usbd_enable(sample_usbd)) {
+		LOG_ERR("Failed to enable device support");
+		return -1;
+	}
+
+	LOG_INF("USB device support enabled\n");
+	return 0;
+}

subsys/usb/device_next/CMakeLists.txt

@@ -104,4 +104,10 @@ zephyr_linker_sources_ifdef(
   SECTIONS class/usbd_dfu.ld
 )
 
+zephyr_library_sources_ifdef(
+	CONFIG_USBD_MTP_CLASS
+	class/usbd_mtp.c
+	class/usbd_mtp_class.c
+)
+
 zephyr_linker_sources(DATA_SECTIONS usbd_data.ld)

subsys/usb/device_next/class/Kconfig

@@ -13,3 +13,4 @@ rsource "Kconfig.hid"
 rsource "Kconfig.midi2"
 rsource "Kconfig.dfu"
 rsource "Kconfig.uvc"
+rsource "Kconfig.mtp"

subsys/usb/device_next/class/Kconfig.mtp

@@ -0,0 +1,35 @@
+# Copyright (c) 2025 Mohamed ElShahawi (extremegtx@hotmail.com)
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config USBD_MTP_CLASS
+	bool "USB MTP Class"
+	help
+	  USB Media Transfer Protocol Device Class support.
+	  Allow file transfer independent of storage file system.
+
+if USBD_MTP_CLASS
+
+config USBD_MTP_MAX_HANDLES
+	int "Max number of Object handles per Storage"
+	default 10
+	help
+	  Maximum number of objects to be handled by MTP, including
+	  stored, removed and added objects.
+
+config RECYCLE_OBJECT_HANDLES
+	bool "Recycle Object Handles"
+	default n
+	help
+	  Recycle object handles when the maximum number of objects is reached.
+	  If disabled, new objects will not be added when the maximum number of
+	  objects is reached. Although this option provide better usability,
+	  it is against the MTP specification.
+
+module = USBD_MTP
+module-str = usbd mtp
+default-count = 1
+source "subsys/logging/Kconfig.template.log_config"
+
+rsource "Kconfig.template.instances_count"
+endif